The aim of this study was to evaluate the dental health conditions of male employees in a large aluminum factory. The present report deals only with the periodontal findings. Five percent of the 181 examined subjects between 25 and 60 yr were edentulous, and all dentate individuals had some degree of periodontal disease. Surfaces harboring stainable plaque were high in all age groups, varying between 65 and 85%. Surfaces without retention factors were 31% and decreased with increasing age. The percentage of sites with bleeding increased from about 40% in the lowest to about 60% in the highest age group. Teeth with probing depths greater than or equal to 4 mm increased from about 30% in the age group 25-29 yr to about 45% in the age group 30-34 yr, after which it increased gradually with increasing age. The difference in bone scores (marginal bone loss) was the most extensive between the ages of 25 and 34 yr, but with a significant increase throughout the age groups. The administrators had a somewhat better oral hygiene, fewer retention factors, less bleeding, fewer pockets and some more marginal bone support than the workers. Still, the administrators had more missing teeth than the workers.